U.S. patent application number 16/731206 was filed with the patent office on 2020-07-16 for bottom nozzle of nuclear fuel assembly provided with flow holes by utilizing layered aircraft airfoil structure.
This patent application is currently assigned to KEPCO NUCLEAR FUEL CO., LTD.. The applicant listed for this patent is Joo Hong Kim Chun. Invention is credited to Joo Hong Chun, Seong Soo Kim, Do Gwan Lee, Nam Gyu Park, Su Pil Ryu, Jong Sung Yoo.
Application Number | 20200227180 16/731206 |
Document ID | 20200227180 / US20200227180 |
Family ID | 71517875 |
Filed Date | 2020-07-16 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200227180 |
Kind Code |
A1 |
Chun; Joo Hong ; et
al. |
July 16, 2020 |
Bottom Nozzle of Nuclear Fuel Assembly Provided with Flow Holes by
Utilizing Layered Aircraft Airfoil Structure
Abstract
Embodiments of a bottom nozzle of a nuclear fuel assembly
provided with flow holes by utilizing a layered aircraft airfoil
structure are provided. The bottom nozzle not only increases
efficiency of filtering foreign substances by minimizing a size of
the flow holes by constituting a shape of flow holes into cross
stripes but also prevents coolant water flow velocity drop through
prevention of coolant water pressure drop by constituting a lateral
sectional shape of the grid frames constituting the cross stripes
into an aircraft airfoil type.
Inventors: |
Chun; Joo Hong; (Daejeon,
KR) ; Kim; Seong Soo; (Daejeon, KR) ; Ryu; Su
Pil; (Daejeon, KR) ; Lee; Do Gwan; (Daejeon,
KR) ; Park; Nam Gyu; (Daejeon, KR) ; Yoo; Jong
Sung; (Park, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chun; Joo Hong
Kim; Seong Soo
Ryu; Su Pil
Lee; Do Gwan
Park; Nam Gyu
Yoo; Jong Sung |
Daejeon
Daejeon
Daejeon
Daejeon
Daejeon
Park |
|
KR
KR
KR
KR
KR
KR |
|
|
Assignee: |
KEPCO NUCLEAR FUEL CO.,
LTD.
Daejeon
KR
|
Family ID: |
71517875 |
Appl. No.: |
16/731206 |
Filed: |
December 31, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G21C 3/3305 20130101;
G21C 3/3206 20130101 |
International
Class: |
G21C 3/32 20060101
G21C003/32; G21C 3/33 20060101 G21C003/33 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 2019 |
KR |
10-2019-0005485 |
Claims
1. A bottom nozzle of a nuclear fuel assembly provided with flow
holes by utilizing a layered aircraft airfoil structure, the bottom
nozzle of the nuclear fuel assembly comprising: a plurality of flow
holes, wherein the flow holes are constituted in a shape of cross
stripes, wherein a plurality of grid frames constituting the cross
stripes is constructed by being stacked while crossing the flow
holes, and a lateral sectional shape of the grid frames is a
streamlined shape of an aircraft airfoil type.
2. The bottom nozzle of the nuclear fuel assembly of claim 1,
wherein the grid frames are constructed by stacking first grid
frames and second grid frames.
3. The bottom nozzle of the nuclear fuel assembly of claim 1,
wherein the lateral sectional shape of the grid frames is provided
to be curved to expand from a direction coolant water flows in and
then to become pointy by being tapered again.
4. The bottom nozzle of the nuclear fuel assembly of claim 2,
wherein the lateral sectional shape of the grid frames is provided
to be curved to expand from a direction coolant water flows in and
then to become pointy by being tapered again.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to Korean Patent
Application No. 10-2019-0005485, filed Jan. 16, 2019, the entire
contents of which is incorporated herein for all purposes by this
reference.
FIELD
[0002] The present invention relates to a bottom nozzle of a
nuclear fuel assembly provided with flow holes by utilizing a
layered aircraft airfoil structure. More particularly, the present
invention relates to a bottom nozzle of a nuclear fuel assembly
provided with flow holes by utilizing a layered aircraft airfoil
structure that prevents a coolant water flow velocity drop through
prevention of coolant water pressure drop while increasing
efficiency of filtering foreign substances.
BACKGROUND
[0003] A nuclear reactor is a device using heat energy generated
from fission as power by artificially controlling a chain fission
reaction of fissile material.
[0004] Nuclear fuel used in the nuclear reactor is manufactured by
forming concentrated uranium into cylindrical pellets of a
predetermined size and then charging a plurality of pellets into
fuel rods. A plurality of fuel rods constituting fuel assemblies is
loaded into the reactor core and then burned up through nuclear
reactions.
[0005] With reference to FIG. 1, in general, a nuclear fuel
assembly includes a plurality of fuel rods arranged in an axial
direction, a plurality of support grids 30 provided in the lateral
direction of the fuel rods and supporting the fuel rods; a
plurality of guide tubes 10 fixed to the support grids 30 and
constituting the skeleton of the assembly and an instrumentation
tube 20 inserted into the center of the support grid 30; a top
nozzle 40 and a bottom nozzle 50 supporting the top and bottom
ends, respectively, of the guide tube 10 and the instrumentation
tube 20.
[0006] A nuclear fuel assembly consists of approximately a number
of 200 or more fuel rods, and enriched uranium is formed into a
pellet of a predetermined size and charged into each fuel rod.
[0007] The top nozzle 40 and the bottom nozzle 50 are for
supporting the upper and lower ends, respectively, of the guide
tube 10, and in order to prevent an occurrence of the lifting of
the fuel assembly by the hydraulic pressure of the coolant water
flowing to the upper portion through the lower portion of the
nuclear fuel assembly, the top nozzle 40 is provided with a
plurality of elastic bodies, thereby functioning to press and fix
the upper end portion of the nuclear fuel assembly.
[0008] The bottom nozzle 50 fixes and supports a lower end portion
of the guide tube 10 and provides holes through which the guide
tube 10 and the instrumentation tube 20 are inserted and a
plurality of flow holes to which the coolant water is supplied.
[0009] With reference to FIGS. 2A and 2B, the bottom nozzle 50 will
be described in detail.
[0010] The bottom nozzle 50 is provided with guide holes 51 and an
instrumentation hole 52 to which the guide tubes 10 and the
instrumentation tube 20 are connected, respectively, and flow holes
53 that are each openings for coolant water to pass through.
[0011] By such a configuration, the coolant water flows into a fuel
rod region through the flow holes 53 and removes the heat generated
from the fuel rods while passing between the fuel rods.
[0012] At this time, when the coolant water flows into the fuel rod
region through the flow holes 53, foreign substances remaining in
the coolant water also enter the fuel rod region along the same
path as that of the coolant water.
[0013] That is, various types of foreign substances flowing
together with the coolant water during the operation of the reactor
pass through the flow holes 53 and enter the region where the fuel
rods of the fuel assembly are located, and may be caught between
the fuel rod and the fuel rod, or between the lowermost support
grid of the fuel assembly and the fuel rod.
[0014] When a foreign substance having a relatively large size is
introduced between fuel rods along with the coolant water through
the flow holes 53, the foreign substance is in vibrating contact
with an adjacent fuel rod cladding, thereby causing mechanical wear
of the nuclear fuel rod cladding resulting in damage to the
cladding.
[0015] As such, the kinds of foreign substances that may damage the
fuel rods are very diverse, such as metal chips after cutting,
debris generated during welding, bolts, nuts, nails, hacksaw
pieces, and the like.
[0016] When the fuel rod cladding is damaged, fission products
generated by the nuclear reaction of the nuclear material in the
fuel rod flow out of the fuel rod cladding to contaminate the
coolant water with radioactive materials. Subsequently,
contaminated coolant water contaminates the entire primary coolant
water while circulating through the primary cooling system of a
nuclear power plant.
[0017] In order to prevent such a problem, the flow holes 53 are
being designed to have various shapes such as a mesh to filter
foreign substances generated in the reactor.
[0018] However, the related art has following problems. First, the
design of the flow holes 53 for improving the efficiency of
filtering foreign substances decreases the coolant water pressure,
whereby a smooth flow of the coolant water is not accomplished.
Next, the design of the flow holes 53 for preventing a pressure
drop of the coolant water reduces the efficiency of filtering
foreign substances.
[0019] The foregoing is intended merely to aid in the understanding
of the background of the present invention, and is not intended to
mean that the present invention falls within the purview of the
related art that is already known to those skilled in the art.
DOCUMENTS OF RELATED ART
[0020] [Patent Document] Korean Patent Application Publication No.
10-2000-0061665
BRIEF SUMMARY
[0021] Accordingly, the present invention has been made to solve
the above problems occurring in the related art, and an objective
of the present invention is to provide a bottom nozzle of a nuclear
fuel assembly provided with flow holes by utilizing a layered
aircraft airfoil structure that minimizes a size of flow holes
through a stacking and crossing configuration, thereby allowing
efficiency of filtering foreign substances to be maximized and, at
the same time, prevents coolant water pressure from being dropped
through the flow holes, thereby ensuring a smooth flow of coolant
water.
[0022] In order to achieve the above objective according to one
aspect of the present invention, there is provided the bottom
nozzle of the nuclear fuel assembly provided with flow holes by
utilizing the layered aircraft airfoil structure, the bottom nozzle
of the nuclear fuel assembly including: a plurality of flow holes,
wherein the flow holes are constituted in a shape of cross stripes,
wherein a plurality of grid frames constituting the cross stripes
may be constructed by being stacked while crossing the flow holes,
and a lateral sectional shape of the grid frames may be a
streamlined shape of an aircraft airfoil type.
[0023] In this case, the grid frames may be constructed by stacking
first grid frames and second grid frames.
[0024] In addition, the lateral sectional shape of the grid frames
may be provided to be curved to expand from a direction coolant
water flows in and then to become pointy by being tapered
again.
[0025] As described above, the bottom nozzle of a nuclear fuel
assembly provided with flow holes by utilizing a layered aircraft
airfoil structure according to the present invention has the
following effects.
[0026] First, the size of the flow holes is minimized by designing
the flow holes in a shape of cross stripes, wherein a lateral cross
section of the grid frames constituting the cross stripes is
applied with a cross section of a shape of the aircraft
airfoil.
[0027] Accordingly, there are effects such that since the pressure
drop of the coolant passing through the flow holes constituted by
the grid frames does not occur, a smooth flow of the coolant water
can be performed, and due the flow holes constituted in a shape of
cross stripes, efficiency of filtering the foreign substances can
be increased.
[0028] Second, a plurality of the grid frames constituting the flow
holes is stacked in a height direction of the bottom nozzle,
wherein the grid frames are installed to cross each other on the
flow holes, thereby causing an effect to further increase the
efficiency of filtering the foreign substances.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The above and other objectives, features and other
advantages of the present invention will be more clearly understood
from the following detailed description when taken in conjunction
with the accompanying drawings, in which:
[0030] FIG. 1 is a view showing a typical nuclear fuel
assembly;
[0031] FIG. 2A is a perspective view showing a bottom nozzle of the
nuclear fuel assembly according to a conventional art;
[0032] FIG. 2B is a plan view showing the bottom nozzle of the
nuclear fuel assembly according to the conventional art;
[0033] FIG. 3 is a plan view showing a bottom nozzle of a nuclear
fuel assembly provided with flow holes by utilizing a layered
aircraft airfoil structure according to an exemplary embodiment of
the present invention;
[0034] FIG. 4 is a perspective view showing a main portion of the
bottom nozzle of the nuclear fuel assembly provided with flow holes
by utilizing the layered aircraft airfoil structure according to
the exemplary embodiment of the present invention;
[0035] FIG. 5 is a bottom perspective view showing the main portion
of the bottom nozzle of the nuclear fuel assembly provided with
flow holes by utilizing the layered aircraft airfoil structure
according to the exemplary embodiment of the present invention;
[0036] FIG. 6 is a bottom view showing the bottom nozzle of the
nuclear fuel assembly provided with flow holes by utilizing the
layered aircraft airfoil structure according to the exemplary
embodiment of the present invention; and
[0037] FIG. 7 is a sectional view showing the main portion of the
bottom nozzle of the nuclear fuel assembly provided with flow holes
by utilizing the layered aircraft airfoil structure according to
the exemplary embodiment of the present invention;
DETAILED DESCRIPTION
[0038] Terms or words used in the present specification and claims
are not to be construed as being limited to usual or dictionary
meanings thereof. Based on a principle that the inventors may
properly define the concept of terms in order to best explain
invention thereof in the best way possible, the terms or words
should be interpreted as having a meaning and concept corresponding
to the technical idea of the present invention.
[0039] Hereinbelow, a bottom nozzle of a nuclear fuel assembly
provided with flow holes by utilizing a layered aircraft airfoil
structure (hereinafter, referred to as "bottom nozzle") according
to exemplary embodiments of the present invention will be described
in detail with reference to the accompanying FIGS. 3 to 7.
Throughout the drawings, the same reference numerals will refer to
the same or like parts.
[0040] The bottom nozzle 100 minimizes a size of flow holes 200,
thereby increasing efficiency of filtering foreign substances and
also ensures a smooth flow of coolant water by preventing coolant
water pressure from being dropped when the coolant water flow
passes through the flow holes.
[0041] Therefore, both of the coolant water flow and the efficiency
of filtering foreign substances may be increased.
[0042] The bottom nozzle 100 is provided with the flow holes 200
through which the coolant water flows therein.
[0043] In this case, the flow holes 200 are provided in a shape of
cross stripes as shown in FIG. 3.
[0044] That is, grid frames 300 are provided in the shape of cross
stripes on a flow plate, thereby providing flow holes 200 each in a
shape of a square.
[0045] As such, as the flow holes 200 are provided in the shape of
cross stripes, the size of the flow holes 200 through which the
coolant water passes may be minimized by increasing thickness of
the grid frames 300, and the efficiency of filtering the foreign
substances may be maximized accordingly.
[0046] On the other hand, the grid frames 300 providing the flow
holes 200 are constructed by being stacked in a height direction of
the bottom nozzle 100.
[0047] In this case, the grid frames 300 are installed crossing the
flow holes 200 while being stacked.
[0048] By such a constitution, the flow holes 200 are constituted
by being divided by a cross shape through the grid frames 300
neighboring in a height direction as shown in FIGS. 3 to 7.
[0049] By constructing the grid frames 300 stacked as described
above to cross each other, the size of the flow holes 200 may be
minimized, thereby increasing the efficiency of filtering the
foreign substances.
[0050] The pressure drop of the coolant water is also to be taken
into consideration as the grid frames 300 are stacked in a
plurality of layers, so the grid frames 300 may be composed of two
layers.
[0051] In this case, for convenience of description, the grid frame
300 installed on the uppermost of the bottom nozzle 100 is referred
to as a first grid frame 310, and the grid frame 300 installed
under the first grid frame 310 is referred to as a second grid
frame 320.
[0052] On the other hand, the flow holes 200 need to not only
maximize the efficiency of filtering the foreign substances but
also prevent the pressure drop when the coolant water flows through
the flow holes 200, so the grid frames 300 providing the flow holes
200 is formed in a streamlined shape of an aircraft airfoil.
[0053] More precisely, as shown in FIGS. 4 and 7, the lateral
sectional shape of the grid frames 300 is provided in a shape of an
aircraft airfoil, wherein the lateral sectional shape is curved to
expand from a direction coolant water flows in and then to become
pointy by being tapered again.
[0054] That is, even when the bottom nozzle 100 is provided to have
a small size of the flow holes 200 due to the construction in the
shape of the cross stripes, with the grid frames 300 as references,
the coolant water flows from each of both sides when passing
through the flow holes 200, and is then guided along the curved
shape of the grid frames 300. Subsequently, the coolant water
merged at a pointy portion of the grid frames 300 flows toward the
fuel rods, so a phenomenon in which the pressure drops when the
coolant water flows into a fuel rod region does not occur.
[0055] Accordingly, as the coolant water flows smoothly through the
flow holes 200 without having a reduction of the flow velocity,
both efficiency of preventing cooling water pressure drop and the
efficiency of filtering foreign substances may be increased.
[0056] The flow holes 200 configured as described above may be
minimized due to the stacked configuration of the first grid frames
310 and the second grid frames 320.
[0057] In addition, the lateral sectional shape of the grid frames
300 constituting a shape of the cross stripes is provided in a
streamlined one in a direction where the coolant water flows,
thereby preventing the pressure from dropping when the coolant
water flows in.
[0058] Due to such a configuration, as shown in FIG. 7, the coolant
water flowing in through the flow holes 200 flows along the curved
portion of the grid frames 300, merges at the pointy portion of the
grid frames 300, and then flows out toward the fuel rods. In this
case, the pressure drop is prevented in the same way as air flow at
the aircraft airfoil passes without a pressure drop, whereby the
coolant water flow velocity is not reduced. Accordingly, the
efficiency of filtering the foreign substances may be maximized due
to a configuration of the compact flow holes 200.
[0059] As described above, the bottom nozzle of the nuclear fuel
assembly provided with flow holes by utilizing a layered aircraft
airfoil structure constitutes the flow holes in the shape of cross
stripes, wherein the grid frames are constructed by being stacked
and crossing one another, and the lateral sectional shape of the
grid frames is applied with an aircraft airfoil shape.
[0060] Accordingly, it is possible to maximize the efficiency of
filtering the foreign substances while maintaining the coolant
water flow velocity as it is.
[0061] Although the present invention has been described in detail
with respect to the described embodiments, it will be apparent to
those skilled in the art that various modifications and variations
are possible within the technical scope of the present invention,
and such modifications and variations are within the scope of the
appended claims.
* * * * *